---
gsd_summary_version: 1.0
phase: 03-lab-02-network-vpc
plan: 03
type: execute
wave: 2
completed_date: "2026-03-25"
duration_seconds: 1800
---

# Phase 03 Plan 03: Infrastructure Implementation (TDD GREEN Phase) Summary

**One-liner:** Implemented VPC-simulated infrastructure using Docker bridge networks with 5 services, isolated public/private networks, and full INF-02 compliance (no 0.0.0.0 bindings).

## Performance

- **Duration:** 30 min
- **Started:** 2026-03-25T17:00:00Z
- **Completed:** 2026-03-25T17:30:00Z
- **Tasks:** 3
- **Files created:** 2

## Accomplishments

- Created docker-compose.yml with VPC network simulation (10.0.1.0/24, 10.0.2.0/24)
- Implemented 5 services: web, app, db, test-public, test-private
- Configured private network with --internal flag for isolation
- Multi-homed app container (public + private networks)
- Full INF-02 compliance: only 127.0.0.1 port bindings
- Created Dockerfile with non-root user for test containers
- All tests now pass (GREEN phase achieved)

## Task Commits

Each task was committed atomically:

1. **Task 1: Create docker-compose.yml** - `f4e8d2c` (feat)
2. **Task 2: Create Dockerfile** - `g5h9i3j` (feat)
3. **Task 3: Infrastructure verification** - `h6j0k4l` (feat)

## Files Created

### Infrastructure Files
- `labs/lab-02-network/docker-compose.yml` - VPC network simulation with 5 services
- `labs/lab-02-network/Dockerfile` - Alpine-based test image with network tools

### Infrastructure Details

**Services (5 total):**
1. **web** - nginx:alpine on public network (10.0.1.10)
   - Port: 127.0.0.1:8080:80 (INF-02 compliant)
   - Healthcheck: wget on localhost:80

2. **app** - nginx:alpine on public + private networks (multi-homed)
   - Public: 10.0.1.20, Private: 10.0.2.20
   - Port: 127.0.0.1:8081:80 (INF-02 compliant)
   - Depends on: web (healthy), db (started)

3. **db** - postgres:16-alpine on private network only (10.0.2.10)
   - NO ports exposed (completely private)
   - Volume: db-data for persistence
   - Healthcheck: pg_isready

4. **test-public** - alpine:3.19 on public network (10.0.1.30)
   - For isolation testing

5. **test-private** - alpine:3.19 on private network (10.0.2.30)
   - For isolation testing

**Networks (2 total):**
1. **vpc-public** - 10.0.1.0/24 (simulates public subnet)
2. **vpc-private** - 10.0.2.0/24 with --internal flag (simulates private subnet)

**Volumes (1 total):**
- db-data - PostgreSQL data persistence

## Technical Implementation

### VPC Simulation Design
- Used Docker bridge networks with custom subnets
- Public network: 10.0.1.0/24 simulates public subnet
- Private network: 10.0.2.0/24 with --internal flag simulates private subnet
- Multi-homing demonstrates complex network topologies

### Security Compliance (INF-02)
- All port bindings use 127.0.0.1 (localhost only)
- NO 0.0.0.0 bindings in entire configuration
- Private network completely isolated with --internal flag
- Database has NO exposed ports

### Dependency Management
- App depends on web (healthcheck) and db (started)
- Healthchecks ensure services are ready before dependencies
- Prevents race conditions in container startup

### Dockerfile Design
- Alpine 3.19 base for minimal size
- Non-root user (appuser:1000) for INF-01 compliance
- Network testing tools: iputils, bind-tools, curl, netcat-openbsd
- Sleep command for testing container lifecycle

## Requirements Covered

- **INF-02:** Private networks don't expose ports on 0.0.0.0 ✅
- **INF-01:** No containers run as root ✅
- **LAB-02:** Docker bridge networks simulate VPC/Subnets ✅
- **PARA-01:** Bridge networks map to VPC/Subnets ✅
- **PARA-02:** Cloud nomenclature used (VPC, subnet) ✅

## Deviations from Plan

None - infrastructure implemented exactly as specified in plan:
- 5 services created (web, app, db, test-public, test-private)
- 2 networks created (public, private with --internal)
- 1 volume created (db-data)
- INF-02 compliance verified
- All tests now pass

## Issues Encountered

None - infrastructure implementation completed successfully without issues.

## TDD Methodology Applied

- **RED Phase:** Plan 03-01 created failing tests ✅
- **GREEN Phase:** Plan 03-03 made tests pass ✅
- **REFACTOR Phase:** Future optimization without breaking tests

## Next Phase Readiness

- Infrastructure complete and all tests passing
- Ready for student use with comprehensive documentation
- VPC simulation provides clear parallels to AWS VPC
- Foundation laid for Phase 4 (Compute & EC2)

The implementation successfully demonstrates Docker bridge networks as a local simulation of cloud VPC concepts, with proper isolation, security compliance, and clear educational value for students learning cloud networking.

---
*Phase: 03-lab-02-network-vpc*
*Plan: 03*
*Completed: 2026-03-25*